Marine actinobacteria are economical and the most valuable group of prokaryotes in the scope of biotechnology which produce secondary metabolites especially antibiotics. Due to extreme living circumstances in marine environments, these bacteria can produce structurally unique metabolites which not seen in soil types. Therefor they have been identified as a source of new drugs. With respect to increase in resistance of microorganisms to available antibiotics in the market, it is essential to discover new drugs. Increasing in the actinobacteria growth is possible by manipulation of nutritional, chemical and physical parameters of cultivation conditions. Optimization of culture medium ingredients has considerable effect on production increasing and costs decreasing. The goal of the current study is molecular identification and optimization of the production conditions of antibacterial agents-producer actinobacteria which have priority to the rest isolates according to their ability of either amount or potency production or in both features. In this study, sampling was done from atomic energy coasts and Jalalieh wharf in Bushehr province. SCB, ISP2, ISP3, ISP4, ISP5, ISP6 and ISP7 medium were used to actinobacteria isolation .Morphological characteristics, biochemical tests, antimicrobial activity and molecular studies were used for identification of antibiotic-producer isolates. Among the antibiotic producer isolates, producing strains which have priority to the rest isolates from the point of amount or potency production or both factors were selected to perform optimization studies using changing one-factor at the time. Several factors including selection the type of suitable inoculating and production medium, pH, incubation temperature, carbon and nitrogen source and incubation time were investigated. Finally, 40 actinobacteria strains were isolated from water, sediment and sponge samples that 75 percent of isolates were antibiotic-producer isolates. Among these isolates, all antibiotic-producer strains had antibacterial effect against gram-positive bacteria, 50 percent of them were effective against gram-negative bacteria and 50 percent of these isolates were effective against both gram-positive and gram-negative bacteria. The 17 percent of isolates also showed antifungal activity. The maximum (optimized) antibacterial activity for both superior strains Microbacterium and Sterptomyces was respectively determined in: ISP5 (medium type), pH 7.0, 27°C, manitol (carbon source) and potassium nitrate (nitrogen source) at the 7th day of incubation; ISP5 (medium type), pH 7.0, 27°C, glycerol (carbon source) and potassium nitrate (nitrogen source) at the 6th of incubation. Besides availability of multiple antimicrobial products, development in epidemic disease spreading, continual emerging of drug-resistant pathogens and development of their transfer among the people, it is essential to perform continual researches in order to achievement of new and effective antibiotic. Also, it is proposed to perform more studies for finding a method by which, production amount of theses isolates reach to the highest level and the lowest cost.
 

Klebsiella pneumoniae is a cause of pneumonia, infection of the urethra and blood. Resistance to Klebsiella strains occurs due to mutations in chromosomal genes, plasmids and transposons. The emergence of resistant strains, which often have the ESBL enzymes, has been resistant to most antibiotics, especially beta-lactam antibiotics. The development of beta-lactam family antibiotics and the creation of new wide-spectrum variants have led to the production of extensive spectrum beta-lactamases or ESBLs that enable bacteria to become bacteria. Making it resistant to a wide range of antibiotics in the β-lactam family. The aim of this study was to determine the prevalence of blaTEM-1, blaSHV-1 genes in ESBL-producing Klebsiella pneumoniae strains isolated from urine specimens, ulcers, and secretions and blood in Ahvaz.
Materials and Methods: Klebsiella pneumoniae isolates isolated from urine specimens, ulcers, and secretions and blood were analyzed by disc diffusion method and double-disc compatibility test after antibiogram analysis. ESBL producing bacteria were identified and after DNA extraction was performed using specific primers for blaTEM-1, blaSHV-1 genes.
Results: 99 isolates of Klebsiella pneumoniae with antibiotic resistance were detected, 54 isolates producing ESBL. After performing the PCR, the blaTEM-1 genes produced SHV-1 were 35.1% and 51.8%, respectively. The highest antibiotic resistance is in the clinical samples related to the antibiotic Nalidixic Acid. And also the lowest antibiotic resistance associated with the antibiotics imipenem, ceftriaxone, and Imipenem.
Conclusion: According to the prevalence of blaTEM-1 and blaSHV-1 genes in Klebsiella pneumoniae strains, they have antibiotic resistance to third generation cephalosporins, in the treatment of infections caused by these pathogens, antibiotic resistance patterns Pay attention.
 

 Among microbial pathogens resistant to antibiotics overuse of antibiotics is created that this makes the need for new therapeutic agents has been discovered. Considering that almost half of the biodiversity of the planet is related to marine organisms, it can be said that sea is a rich source for new compounds. So, in order to advance in the field of pharmaceutical activities, the reservoir is a valuable natural molecule. Among marine microorganisms, actinobacteria are of particular importance because they produce various chemical compounds with a wide range of biological activities. Therefore, the quest for the discovery of unknown microbial strains from this relatively virgin reservoir is an effective way to obtain new bioactive compounds. In this regard, the present study has focused on the isolation of actinobacteria from Bushehr coast, which is still considered as a microbiological research. In this project, 7 types of environment were used for separation of actinobacteria from two atomic energy stations and Jalaliyeh port, Bushehr port. Morphological, biochemical and molecular studies were used to identify antibiotic isolates. 40 isolates of actinobacteria were isolated from water, sediment and sponge samples, 30 isolates were active antibacterial activity, in other words 75% of antibiotic isolates were antibacterial activity against 100% Gram-positive bacteria, 50% against gram-negative bacteria and 50% against both gram-positive and gram-negative bacteria. Also, they showed about 17% of antifungal activity. The antibiotic producing strains 26, 30, 32, 38, 39 has anti-bacterial and anti-fungal.. The findings of this study showed that useful and diverse marine actinobacteria can be easily isolated from Gulf waters to produce antibiotic compounds. Given the vast expanse of the Persian Gulf coast in southern Iran, this source can be a major new place for the separation of actinobacteria.

 Mycotoxins are natural products with low-molecular-weight that produced by filamentous fungi as secondary metabolites. The most important mycotoxins in terms of agro-economic and public health are FUM, AFT, OTA, ZEA and Trichothecene. The presence of these mycotoxins in food are very important and they are found in more than 100 kinds of agricultural products including corn, soybeans, wheat, rice, nuts and etc. With respect to the abundance of mycotoxins and focus on their toxicity and carcinogenesis in scientific communities, the investigation of the amount and the type of mycotoxins in imported cereal, the aflatoxin's amount and isolation of aspergillus from produced rice in Khuzestan were done in this study.
For this reason, the presence of mycotoxins such as AF, OTA, ZEN and DON were investigated in 2750 samples of referred cerebral to laboratories around the Ahwaz city which HPLC method was used for their detection and quantification. Also, the 50 rice samples from farmers were collected and in addition to the investigation of the presence of aflatoxins, Aspergillus strains were isolated with cultivation of rice seeds on SDA medium. Identification of isolates was done according to the macroscopic, microscopic and molecular characteristics.
According to the gathered results from HPLC and with respect to the standard number 5925 in Iran, the amount of OTA, DON and ZEN mycotoxins in three seeds (barley, corn, wheat) were in standard range, but B2 and G2 aflatoxins in corn samples were 0.4% and 0.1% above the standard level (5ppb), respectively. Apart from B1 aflatoxin (which in 2% of rice samples was above admissible limit), other aflatoxins didn't observed or were in the standard limit.
The gathered Aspergillus isolates in the present study were included: 42.1% Aspergillus flavus, 21.05% Aspergillus niger, 15.7% Aspergillus tuningensis, 10.52% spergillus terreus, 5.26% Aspergillus nidulan and 5.26% Aspergillus sp .

  Infectious diarrhea continues to be one of the major causes of morbidity and mortality affecting children under five years old in developing countries. Diarrheagenic Escherichia coli (DEC) is a major etiologic agent among pathogens that cause diarrhea in children.
To investigate the occurrence and pathotypes of DEC among children, under five years of age, living in the province of Khouzestan, Iran, 208 diarrhea samples were screened by multiplex-PCR. The putative DEC isolates were investigated for resistance to various antibiotics as well as production of extended-spectrum beta-lactamase (ESBLs). Moreover, phylogenetic groups were determined by multiplex PCR.
A total of 58 (27.9%) DEC isolates were identified from 208 diarrhea samples, including 35 enteroaggregative E. coli (EAEC) (16.8%), 10 enteropathogenic E. coli (EPEC) (4.8%), 6 enteroinvasive E. coli (EIEC) (2.9%) and 6 enterotoxigenic E. coli (ETEC) (2.9%).The enterohaemorhagic E. coli (EHEC), however, was not identified in any diarrhea samples.One of DEC isolates showed genes related to both EPEC and EAEC pathotype. High resistance profiles were observed to Ceftazidime, followed by Ceftizoxime, Ceftriaxone, Cefotaxime, Cefoxitin ,Gentamicin ,Amikacin , Ciprofloxacin and Imipenem, were also found to be effective antibiotics. More than 65% of pathogenic isolates were showed a multidrug-resistant (MDR) phenotype. The overall incidence of ESBL-producing strains was 79.3% of all DEC isolates. Phylogenetic group B2 was the most predominant group with a frequency 44.8%.
Overall, our findings reinforce the importance of the role of DEC isolates in the etiology of diarrhea in children. It was recovered that EAEC has a high rate among diarrhea samples, indicating a wide spread of this pathotype among study population. To prevent outbreaks and reduce sporadic cases of diarrhea, its causative agents should be determined. The progressive increase in antibiotic resistance among DEC isolates makes it imperative to implement policies to control the spread of resistant bacteria.

Nowadays, bacterial infections, especially those caused by multidrug-resistant bacteria are became one of the major challenges for healthcare programs. Staphylococcus aureus is a major cause of nosocomial and community-acquired infections and due to the virulence potential and increasing resistance against antimicrobial drugs has become one of the most important health problem worldwide. Understanding the epidemiology and the distribution of this bacterium in the community as well as the hospital is necessary to determine the source and so limit its spread. Finding a suitable indicator for this purpose in recent years has been considered. Therefore, due to the prevalence of infections caused by S. aureus methicillin-resistant strains and the importance of genotyping of resistant strains to find the source of contamination and infection control, the aim of the present research was study of molecular diversity of methicillin-resistant S. aureus isolates from patients admitted to hospital. In this study 100 S. aureus isolates, sampled over a 6 months period (April to September 2015) from Golestan and Razi hospitals, were used. By phenotypic and genotypic tests, 50 isolates were identified as methicillin-resistant strains. Four different genes of MRSA including coa, spa, aroA and gap were searched. The MRSA isolates were typed using PCR-RFLP. Amplification of coa gene were identified, 8 types and spa gene identified, 5 types and 11 subtypes. Digestion of coa gene and gap gene PCR products with AluI enzyme, revealed 13 and 3 types, respectively. While Digestion of spa gene PCR product using HindIII enzyme, revealed 13 types, and Digestion of aroA gene PCR product with TaqI and RsaI enzymes, revealed 4 and 6 types. This study showed that PCR-RFLP analysis, has discriminatory power, reproducibility, and is easy to interpret and can be considered as a promising alternative for the epidemiological typing of S. aureus isolates.

Clostridium difficile is a spore-forming, obligate anaerobic, gram positive bacilli that is acquired from the environment or by the fecal-oral route. In human C. difficile is the cause of antibiotic associated diarrhea (AAD) and pseudomembranous colitis. When the normal intestinal microflora change, by risk factors such as treatment with antibiotics, treatment chemotherapy and etc, C. difficile being to be propagation and can cause disease. The main pathogenesis factors of these bacteria, are both the A and B toxins, which are encoded by tcdA and tcdB genes. Diarrhea is the most common infection disease in third world countries and is one of the health concern. In this case diarrhea associated with C. difficile is the most common cause of hospitalized diarrhea. To investigate prevalence of C. difficile infant of Ahvaz, a total of 125 stools specimens from patients with and without antibiotic-associated diarrhea were collected from Ahvaz Abouzar hospital. Stool samples after treatment with enriched in cooked meat broth and heat shock and alcoholic shock were cultured on CCFA and incubated anaerobically at 37°C for 5-7 days. After identifying C. difficile isolates based on biochemical tests, for the detection presence of toxins and confirmed isolates, PCR was performed by three gene tpi, tcdA and tcdB and for evaluation of toxins production, filtered extract bacteria were treated with Hela cell culture. Antibiotic sensitivity of isolates also determined. Totally 21 samples were positive for C. difficile. Of those 21 isolates, 15 were positive for toxin genes that 13 of these had cytopathic effect on Hela cells.

Influenza virus A is an important and worldwide viral disease that causes significant economical losses in poultries. It also is a major causative agent for morbidity and mortality around the world that annually affects significant portion of human population. So, its rapid diagnosis is of great importance. The aim of the present study is to construct an Antigen Capture ELISA (AC-ELISA) for diagnosis of this virus. For this purpose, the nucleoprotein (NP) of virus captured by monoclonal antibody (D'C4) and then using rabbit polyclonal antibody it was recognized. The sensitivity and specificity of this method were also evaluated. The results revealed that constructed AC-ELISA did not have any cross reaction with other viral and bacterial pathogens of poultries while it was able to detect avian influenza virus H9, as well as H1 and H3 types of human influenza. The sensitivity of AC-ELISA was 10 times higher than HA test, and had comparable sensitivity with RT-PCR method. Furthermore, this method was able to recognize influenza virus in tracheal swabs of experimentally infected chickens following 3-5 days of infection. Based on the obtained results it can be concluded that the AC-ELISA is a sensitive and specific method for detection of infections caused by H9 serotype and probably other serotypes of avian influenza virus in clinical samples.

 Legionella specially Legionella pneumophila is important as a causative agent of infectious in human respiratory system and is major cause of legionnares disease in human . These Bacteria are water-born organisms with a wide distribution in natural environmental water supplies which have led to many of pneumonia outbreaks so far. Legionella genus has 51 spieces that wich 23 of them are pathogen for human. Legionella is a thermophilous bacterium, therefore identification the main sources of this organism, specially in tropicial regions and using predictive functions in first step and treatment acts subsequently will be effective in preventing this bacterium distribution. Today many different methods have been introduced for identification of Legionella,which culture on selective and nonselective mediums and PCR are two most important methods. This study was performed for isolation and identification of Legionella from different water sources of Ahvaz city and to compare rate of Legionella distribution in these areas in order to detect the main sources of Legionella. For this purpose water samples have been collected from different sources of the city such as hospitals, entertainmental waters, residential waters, rivers and ect. These samples first were surveyed by culture method. After centrifuging and acidic treatment these samples were cultured on nonselective medium of BCYE and selective medium of MWY. Then positive samples were cultured on blood agar and macConkey agar that lac of growth on these mediums was a sign that samples are positive. In the next step of study for final confirmation the positive samples were performed by PCR method. In PCR reaction, primers of 16S rRNA, that are special for Legionella species, were used for replicating the DNA sequence with 650 bp. In result, 13 samples (18.6%) were positive and all of these were confirmed by PCR method. Most of samples that were positive had relatively high temperature and were sampled in warm seasons.

 Diarrhea is a digestive disorder and the common cause of children mortality in developing countries. Among the bacterial pathogens, diarrheagenic Escherichia coli pathotype (DEC) is one of the most important causes of endemic and epidemic diarrhea in the world. In 2014 (April to November); stool culture results of 578 children under 10 years (311 male, 267 female) referred to Shahid Madani Hospital of Khorramabad were reviewed for a cross – sectional study to isolate diarrheagenic E. coli isolates. The samples were initially cultured on MacConkey agar medium and then pink colonies (lactose positive) were cultured on EMB agar. In order to assess the presence of E. coli O157: H7, samples were also cultured on sorbitol MacConkey medium containing cefixime and tellurite. Authentication of E. coli strains were performed by differential biochemical tests. Among 578 stool samples from children with diarrhea, 186 E. coli isolates were diarrheagenic, so they were studied by Multiplex PCR to determine the group of diarrheagenic E. coli isolates (four pathotypes of ETEC (Enterotoxigenic E. coli), EPEC (Enteropathogenic E. coli), EIEC (Enteroinvasive E. coli) and STEC (Shiga toxin-producing E. coli)) in order to identify lt, st, bfpA, eaeA, stx1, stx2 and ial genes. The most isolated groups among the studied pathotypes of ETEC, EPEC, EIEC and STEC were ETEC (15%), EPEC (14%), STEC (9.7%) and EIEC (4.83%), respectively. Serotype E. coli O157: H7 was found in none of the isolates. Based on the results, it can be expressed that four pathotypes studied are important factors in children with diarrhea and new methods should be used to identify them

 Helicobacter pylori is the most important factor in human gastritis and indigestion that has worldwide outbreak, According to the Importance of this bacteria and different prevalence of that in different parts of the country; and The purpose of this survey was to determine the prevalence of H. pylori infection in Ahvaz.
This study is a descriptive-sectional survey on 100 patients that have problem in Gastrointestinal and gone to Imam Khomeini hospital in Ahwaz in 2015. First, the rapid urease test (RUT) and polymerase chain reaction (PCR) was used to detect H. pylori. Then The SPSS software and chi square test and analysis of variance to find an association between Helicobacter pylori infection and patient characteristics were used.
Of the studied patients , 68% were infected with H. pylori infection. The results showed that between the level of education and clinical symptom of acid reflux and infection with bacteria, is a significant relationship, But between age, gender and infection with Helicobacter pylori, didn't observe a significant relationship.
in this study, the incidence of false-positive results in the rapid urease test and according to evidence from previous studies, using PCR due to higher sensitivity and specificity than the urease head was chosen as the gold standard.
according to high prevalence of H. pylori infection and its complications in infected people; continuous Supervision, health education and strict control of reinfection in the Studied population is necessary.

 Enterohemorrhagic Escherichia coli and Salmonella enterica, are microbial agents that can be transmitted to humans through food and caused dangerous diseases such as hemorrhagic colitis and hemolytic uremic syndrome (by EHEC) ; typhoid and Para typhoid (by Salmonella enterica) in humans.
In this study, 256 samples of fresh vegetables such as lettuce, cabbage and herbs were collected from 4 wholesalers in the city of Ahvaz over a period of 8 months.
After initial enrichment, the CT-SMAC and XLD media were used to detect sorbitol negative E. coli and Salmonella respectively. Detected isolates transferred to the differentiate and specific biochemical media for final confirmation. E. coli isolates were tested by O157 and H7 antisera. Salmonella samples were also tested by specific antisera.
Antimicrobial susceptibility testing was performed by disk diffusion method for Salmonella isolates. Finally, the presence of stx1, stx2, eaeA and hlyA genes in negative sorbitol E. coli samples were studied by multiplex PCR. Out of 256 samples, 12 (6.4%) and 8 (1.3%) samples were related to Salmonella enterica and E. coli O157 respectively. Two isolates were detected as E. coli O157: H7.
Multiplex PCR showed that 4 isolates are positive for stx1, 2 isolates for stx2, 1 isolate for stx1 and eaeA genes, 1 isolate for stx1, eaeA and hlyA genes and 1 isolate for stx1 and hlyA. None of these isolates were contain all 4 typical genes of E. coli O157:H7.
Antibiogram tests on Salmonella isolates showed that 7(58/3%) samples are resistance to at least one antibiotic, and 3 (25%) isolates are simultaneously resistance to 2 antibiotics.
Serotyping of Salmonella enterica showed that 6, 4, and 2 isolates are located in three serogroups of D, C and B respectively. None of these isolates are related to A serogroup.
The presence of these bacteria in vegetables is problematic for public health and can lead to the outbreaks of food-borne diseases. Thus the importance of healthy vegetables before consumption is increasingly clear.

Gastroenteritis is a common disease in the current century. Various factors, including bacteria, viruses and parasitesas its main factors play roles in the occurrence of this disease. In this study, we investigated viral-type rotavirus. Rotavirus causes gastro entries in children under 5 years of age, especially in children under 2years old. Severity of the complication of this disease in children can be reduced by vaccination, as well as by early detection and treatment of disease as well as reduced vaccine against this virus is possible for children immunization. The purpose of this study was to evaluate the incidence of gastrointestinal infection caused by rotavirus in children under age of 5 with diarrhea and vomiting. Techniques for the detection of the ELISA, latex agglutination and RT-PCR were used to identify patients with rotavirus infection.200 fecal samples were collected from January 2014 to September 2014. All three methods were tested for the first 100 samples and the performance of these 3 tests in diagnose accuracy, sensitivity and especially were compared and determined. The result of the studies on these 200 samples showed that 82 samples were positive by latex test of these 42 samples, 21% of the prevalence were detected by RT-PCR as positive. The highest prevalence of the disease was in March rated at 30.95 % and the lowest was in September rated at 2.38 %. In the current study there is a senseful relation between the incidence, clinical symptoms of diarrhea, vomiting and fever, rated at 0.05 % comparing the 3 experimental methods tested on the first 100 samples for detection speed high sensitivity and fine specificity, ELISA was rated at 96 % for sensitivity and 85 % for specificity.

Probiotics are specific live microorganisms that, if used with sufficient amounts in the human or animal, they can cause beneficial effects on the host’s health by affecting body’s microbial flora. Some of these beneficial effects are: to prevent the growth and activity of pathogenic bacteria, reduce cholesterol and blood lipids, improve lactose digestion and reduce lactose intolerance, prevent and reduce intestinal disease and cancer, strengthen the body’s immune system. Most probiotics belong to a large group of main bacteria in the human intestinal flora in where they have harmless commensalism life. The most important probiotic bacteria belong to the genera Lactobacillus and Bifidobacterium. The study aims to isolate probiotic bacteria from different natural sources and their effects on lowering blood cholesterol levels in rats. Accordingly, in this study, different sources were sampled (various local dairy products (yogurt, milk, and cheese), probiotic yogurt, carrots, cabbage, Tarhana and stool). After enrichment, dilution and culturing on specific medium, final purification was performed (in 2 ways: separation under aerobic and anaerobic conditions). Early identification was performed by a variety of biochemical tests. Selected isolates were identified by 16s rRNA gene sequencing. A total of 34 isolates were isolated, one isolate was selected randomly from each source and finally, 1o selected isolates are: 2 isolate of Lactobacillus plantarum (from Carrot and cabbage), 2 isolates of Bacillus subtilis (from cheese and stool), 1 isolate of Weissella paramesenteroides (from yogurt), 1 isolate of Enterococcus faecium (from Tarhana), 2 isolates of Lactobacillus gasseri (from stool under anaerobic conditions), 1 isolate of Lactobacillus fermentum (from stool under anaerobic conditions) and 1 isolate of Lactobacillus brevis (from stool under anaerobic conditions). After preparing 40 rats in 8-membered 5 groups, after 2 weeks of consuming high-fat (cholesterol-containing) foods by 3 groups of rats (for hyperlipidemia), followed by 2 weeks of consuming 10 selected isolates in rats tested, LDL and cholesterol were significantly reduced and decrease in triglycerides was observed, but not significantly. Also, a significant increase was seen in HDL increase. According to the results, genus Lactobacillus showed the highest effect on lowering cholesterol and harmful fats compared to other genera isolated.

 Production, Distribution and Widespread use of Methyl Tert-Buthyl Ether (MTBE) has resulted in a large number of contaminations in growndwater, drinking water sources and soils. MTBE is stable in the environment and on the other hand MTBE has been identified as a suspected carcinogen, even at very low concentrations, Thus importance of their remediation is pointed. During recent years, Bioremediation has emerged as an alternative technique for MTBE removal due to its cost-effective and environment-friendly properties. The aim of this study was to isolation, screening and selection of MTBE degrading bacterial from MTBE-contaminated soils and the effluent of MTBE plant of petrochemical Bandar Imam Bacteria and optimize the degradation by bacteria isolated to remove this contaminats from the environment. In this study, Enrichment technique was used to isolate MTBE degrader. 28 different bacterial strain were isolated by enrichment culture with five consecutive selective transfers. Then of enrichment, for screeninig of these 28 isolates, superior isolates were selected by growth in high concentration of each compound in liquid and agar-BSM medium. Biodegradation rates of compound were determined by Gas Chromatography (GC) . After 21 day ancubation in liquid BSM with 200ppm MTBE, isolates of Soil including PMS, PMA, PMB, PSSA and PM54, degraded 99/23, 98/85, 91/29, 86/499 and 53/505 of MTBE.,respectly and results of GC analysis for PWA, PWB,PWC, E8 and A12 of effluent isolates 92/02, 91/305, 97/155, 89/545 and 88/515, respectively. Result of GC analysis showed that efficiency of consortium with 3 strain PMS, PMA and PWC in degrading of MTBE is more than monoculture isolates. Based on biochemical teste and 16SrRNA gene sequence analysis, the isolate of PMA was identified as Pseudomonas putida KT2440 and isolates of PMS to Klebsiella variicola At-22, PMC to Azotobacter vinelandii DJ and isolates of PWA and PSSA to Pseudomonas aeruginosa and PWC to Enterobacter Oryzendophyticus have maximum identify. At the end, Optimized the degradation was perfopmed by the best strain, PMS. In order to enhance its degradation ability, selected environmental factors were investigated. The results showed that the optimal temperature was in the range of 25-30℃. and pH was 7.0.

Multidrug resistance microorganisms play an important role in many clinical problems globally. Therefore, there is an urgent need for developing new drugs which are effective against current antibiotic resistante pathogens. Around 23000 bioactive secondary metabolites produced by microorganisms have been reported. Over 10000 of these compounds are produced by actinomycetes, representing 45% of all bioactive microbial metabolites discovered. Among actinomycetes, around 7600 compounds are produced by Streptomyces species. As the frequency of novel bioactive compounds obtained from terrestrial Streptomyces species decreased, it had been emphasized that Streptomyces sp. from marine environments might be valuable for the isolation of novel strains which could potentially yield a broad spectrum of secondary metabolites such as antibiotic. The aim of this study was isolation and characterization of marine Streptomyces sp. from Persian Gulf in order to finding novel antibiotic compounds against some pathogenic bacteria. In this regard, the samples of water and sediment were collected from the some northwest areas of Persian Gulf. Thirty-five putative strains isolated and assessed for antibiotic production and activity against a wide range of bacteria including reference strains and clinical isolates. In this way, Inhibition effects of these strains were assessed against 6 Gram positive and 6 Gram negative bacteria by top agar layer method. Totally seventeen of them showed the ability to produce antibacterial compounds. From these isolates, three isolates (MW-4, MW-5 and BW-5) with high potential antibiotic producing were selected for further tests. All three isolates were effective against both Gram positive and Gram negative bacteria. Inhibition zone of the ethyl acetate extracts were found to range between 10-28 mm diameters at a concentration of 50 mg/ml. Finally Characterization of the best producers was carried out by morphological, physiological, chemotaxonomic and biochemical methods. All three isolates were identified as Streptomyces Species. Also Definite identification of MW-4 isolate was confirmed by 16S rRNA sequence. Finally this isolate was identified as Streptomyces enissocaesilis. The current investigation reveals that the marine Streptomyces sp. from the Persian Gulf could be potent source of novel antibiotics and can give hope control of the disease caused by multidrug resistant bacteria.

 

Abstract:
Petroleum reservoirs are subsurface of short-chain and long-chain (C1-C30),linear, cyclic and branched alkanes. Natural gas seeps from oil reservoirs to the earth’s surface where it can enter into the earth’s atmosphere. A fraction of the natural gas seepage is consumed by hydrocarbon-oxidizing (HCO) microorganisms that reside in the soil. These HCO microorganisms can utilize short-chain alkanes (C1-C4) as their sole source of energy and carbon. Geo-microbial prospecting for hydrocarbons is an exploration method which is based on the seepage of light gaseous hydrodrocarbons from oil/gas reservoirs towards the surface and their utilization by hydrocarbon-oxidizing bacteria. The methane-oxidizing bacteria usually have been used as indicator microbes for prospecting of oil and gas. The aim of this study was isolation and characterization of those bacteria which are capable of to methane consumption as the sole source of carbon and energy. Soil samples were collected from the oil and nonoil regions. The bacterial suspension was prepared and inoculated into NMS (Nitrate mineral salts) broth medium. Then atmosphere of the flasks were filled up with 50% of methane and 50% of air. Incubation was performed on the shaker for 10 days. In addition, the gas mixture was renewed every 2 days. Then liquid culture samples were spread onto NMS agar plates. The plates were incubated for 2 weeks in a gas-tight jar with similar gas composition as mentioned above. Single colonies that formed on the NMS agar plates were transferred onto fresh NMS agar plates and then incubated for another week. Growth curve of these isolates was obtained in different various pH and temperatures. These isolates were identified by biochemical tests and sequencing of 16S rRNA gene. Finally,three isolates were identified as Sphingomonas sanguinis, Sphingomonas parapaucimobilis and Achromobacter xylosoxidans from petroliferous and likely presence of oil regions. Optimized conditions growth for by three strains were 30˚C and pH 7.4. Finally, based on these results it can be concluded that these isolates are methane consumers that can be applied as indicator microbes for prospecting of oil and gas.